The next time I had the dream, I paid special attention to the key.

     This time, I was carrying something as I walked along the corridor. Something wrapped up in a sack that I had sIung across my shoulder. It was quite heavy, but in the dream I was strong enough to carry it quite easily. As before, I reached the room at the end of the corridor, opened the door and descended the long flight of steps until I came to the strong wooden door at the bottom.

     I took the key from my pocket, but before I inserted it into the lock I held it up in front of my eyes and looked at it. It was made of bronze and had a couple of gems inlaid in the handle. That was good for two reasons. Bronze was highly corrosion resistant. If it had been left in the burning mansion, it might well have survived, buried somewhere, until the present day. I might well be able to find it with a metal detector. Of course, even if it was still on the grounds somewhere, it might well be under the house. Or under one of our neighbours’ houses. It was a chance nonetheless, and I decided to order a metal detector first thing in the morning.

     The second good thing was the gems. Garnets by the look of them. Not as valuable as rubies but still worth a bob or two to a collector. George, our next door neighbour, had told us that the cook had survived the fire, along with her young child. Homeless, without a job or any other means to support herself or her child, she might well have grabbed any valuable object on her way out, to sell for money. Maybe the key was one of the things she'd grabbed. It might well be in someone's collection, sitting in a drawer somewhere.  Tipping’s shop had a drawer full of keys, although not one resembling the one my dream self was holding in his hands. I could put the word out, though. Let other antiques dealers all across the country know that I was looking for it. People in my line of work did things like that all the time. There were websites where dealers could put the descriptions of objects they were looking for, and if anyone in the country, or anyone in the world, had seen it, they would let me know.

     As always, the dream ended as I placed the key in the lock and I found myself awake in our bed, Sophie cuddled up beside me. I couldn’t rest, though, and carefully got out of bed without waking her up. I turned on my laptop, began sending emails to my contacts in the antiques world and ordered a metal detector. Only when I had done that was I able to relax enough to get back into bed and go back to sleep.

     I’d selected next day delivery for the metal detector, and it arrived in the middle of the next afternoon. For the next couple of days, Sophie watched pityingly as I walked around the garden with the device in my hands, pulling up the long strips of dying grass whenever it beeped to see what lay beneath. Before long I'd found vast numbers of coins and rusty nails, but nothing else. I also used the device indoors, marching across the carpeted rooms of our house with it. Every nail in the floorboards made the thing beep, of course, but I’d hoped that if there were a larger object down there it would cause the device to make a louder beep. If it had, I know that nothing would have prevented me from ripping up carpet and floorboards to see what it was. Sophie would have been beside herself with fury and consternation, but she wouldn't have been able to stop me. Fortunately, though, the device gave no indication that there was any large metal object hidden under the house.

     Replies began to come to the emails I'd sent. Apologies mostly, along with suggestions of other people I could ask. I began to wonder how long I would give it before I simply broke down the strong wooden door in the basement, my curiosity finally stronger than my need for caution. Sophie saw my distress, of course, and asked me whether I was becoming obsessed with the door. I snapped back at her impatiently and she withdrew with a hurt look on her face. Once, I would have rushed to apologise to her, but now her feelings seemed trivial and unimportant. Somewhere along the line I'd stopped being in love with her. She was now nothing but an attractive woman that I shared the house with. This discovery didn't bother me, but I was careful to keep her from finding out because I didn't want to be distracted by her emotional outbursts.

     Then I received an email from a contact I'd only met face to face on one occasion, a collector based in Exeter who specialised in silver and jewellery. He sent me a photo of a key he had in his possession and my heart raced with excitement when I saw it. That was it! That was the key to the door in the basement! I immediately sent him back an email asking him how much he wanted for it and he sent a reply naming a price. I agreed immediately and he told me that it would put it in the post straight away. It should get to me within a day or two.

     Sophie was pleased by the news, but only because it meant that it would all soon be over. I would open the door, see there was nothing behind it but an empty room with slimy stone walls and our lives would go back to normal. She started humming again as she went about the housework, and she smiled and laughed the way she'd always used to. I frowned and worried whenever I saw her talking to the neighbours, though. I’d made it clear to her that I didn't want them to know about the basement, but I worried that she might forget herself in her happiness and let something slip out. I began to wonder whether I needed to do something to silence her permanently.

     Just in case that turned out to be necessary, I suggested to her that she might want to visit her sister in Australia, whom she hadn't seen in over three years. I won’t be able to go with you, I told her, because Frank Tipping needs me in the shop, but there’s no reason why you can't go by yourself. The suggestion puzzled her, but she mentioned it to the neighbours, which was what I'd wanted. If she suddenly went missing, everyone would assume it had happened while she was on her way to Australia. I even bought a single ticket for a flight to Brisbane. The airline company would tell the police that she'd never turned up for the flight, but it was a long way between here and Heathrow.

     When the parcel arrived, I ripped it open almost before I'd taken it from the delivery man. There was the key, just as I remembered it from the dream. The bronze gleamed like new, its previous owner had taken good care of it, and the garnets glittered in the light of the afternoon sun. I had to overcome a powerful temptation to rush out into the garden, run down the stairs and try the key in the lock immediately. Only the knowledge that the neighbours couldn't help but see stopped me. I had to wait until the deep of night.

     I wanted to go alone, and so was pleased when Sophie declined to come even before I'd suggested she stay behind. “That place creeps me out,” she said. “I'm never going back down there. Just tell me what you find when you get back.” I told her I would, and so when midnight came I collected the key and my night vision goggles and went out into the garden.

     It had rained during the day and some if it had found its way under the boards covering the opening. They’d made the steps slippery and treacherous and I had to take care on the way down in case I lost my footing. When I reached the bottom, though, I stopped dead as I realised that there was something different about the place this time. There was a different feel to it. I wondered whether it was because I was alone this time, but then I realised that there were sounds coming from behind the door. There was something moving in there. Also, when I removed the goggles to wipe the sweat from my face, I saw that there was a faint glow coming from under the door. A greenish glow, giving the impression of being biological rather than electric, as if there was a cloud of fireflies in the room. Fear gripped me, but I knew that if I left, my desire to know would pull me back almost immediately, and so I took the key from my pocket and put it in the lock.

     It was the first time the lock had been turned for almost a hundred years and its workings had seized up, but the key was strong and I was able to put a considerable force on it. Eventually, whatever had been jamming the lock gave way and it turned. Then I turned the handle and pushed the door open. It was hard to move with all the detritus that had collected on the floor under it and the hinges squealed. I glanced nervously back up the stairs, but I doubted the sound would have carried that far. Relaxing, I put all my strength to it and forced the door open. Eerie green light spilled out into the stairway, and I understood why the room was so far underground. I took a step forward and looked in.

     The moment I saw what was in the room, my memories returned. My real memories. Charles Towen was just one of the names I'd had down through the centuries. The caretaker had stabbed me, I remembered. He’d done it when he discovered that his child, his wife's child, was in fact my child. He then set fire to the house and went in search of the baby, intending to kill it as well. I’d lived long enough to cast a Bane on him, though, and then, with my last breath, I’d cast the spell to send my soul into the future, to seek out the grandson of the child the cook carried as she fled from the burning house in terror. That’s how it works, you see. My soul can only inhabit a body that carries my own blood. I can only possess my own descendants. That's the way it's been for at least the past two thousand years, the furthest back my clearest memories go.

     As my memories returned, so did the burden of responsibility. It was my job to safeguard this cellar and the thing that it contained, a task that had been entrusted to me so long ago that it had been possible to walk from England to Europe. I now knew what I had to do. It wouldn’t be pleasant, but it was necessary if this country that I loved was to be protected.

     I left the room, closed and locked the door, climbed the stairs and returned to the house. I hurried up to the bedroom, but then had a thought and went back to the cupboard under the stairs to get a hammer and a length of thin but strong rope. I tucked them out of sight in my clothes before going back up the stairs to wake Sophie. “Get dressed!” I told her. “You've got to see what’s down there! You won’t believe it!”

     “Just tell me,” she said sleepily, pushing the hair back out of her eyes.

     “You won’t believe it unless you see for yourself. Hurry up, get dressed.”

     She grumbled, but got out of bed and began pulling on her clothes. “This had better be worth it,” she said as she fastened her bra behind her back. “I was in the middle of a really good dream.”

     “When you see what’s down there, you'll think you’re still dreaming,” I promised her.

     She eyed me doubtfully but continued getting dressed while I waited impatiently. Then she followed me out of the house. I urged her to keep as quiet as possible as we crossed the garden. “The need for secrecy is greater than ever,” I told her. “You haven't told anyone, have you?”

     “Of course not. You asked me not to. What's down there, then? Treasure?” Her eyes widened when I didn't reply. “Oh my God! It is, isn't it? There's treasure down there, isn't there?”

     “Keep your voice down,” I warned her.

     She nodded vigorously and hurried on. She reached the staircase before me and hurried down it, and I hurried to catch up as I remembered I'd forgotten to warn her about the treacherous stairs.

     We both reached the bottom safely, though, and I arrived to find her pulling at the door. “You locked it again?” she said accusingly.

     “Just to be safe,” I said, producing the key. I unlocked the door and Sophie pushed past me to go in. Her face was radiant with excitement, but when she saw what the room contained it was replaced by a look of shock, and then horror. She spun around to face me...

     I hit her head with the hammer and she fell like a stone. She wasn’t completely unconscious, but she was dazed enough that she wasn’t able to stop me from removing her clothing and tying her hands and feet. “What...” she said woozily as I pulled the knots tight. “What... doing...?” Blood trickled down from the cut in her head to gum her silky hair against her face. Seeing it made me feel bad, but some things just couldn't be helped. The proof of that was right there in the room with her.

     As if reading my thoughts, she turned her head and looked at it again. “What, what that?” she asked, her voice still slurred. She tugged at her bound wrists. “Untie... untie...” She shook her head as if struck by a bout of dizziness.

     The thing in the room looked like a monstrous maggot the size of an elephant, but with two almost human looking arms. Two clusters of three eyes were arranged on either side of its body, near its mouth end. They were open but seemed unfocused, as if the creature was intent on its own thoughts. The very slightest of movements in its swollen, segmented body testified to the fact that it was a living creature, and not merely an incredibly lifelike statue. It seemed unaware that there was anyone in the room with it.

     “That is Mull Vom,” I told her. “It is a God and I am its keeper. It is my job to keep it from devouring most of the population of this country.”

     She stared at me as if I were mad. Then she opened her mouth and screamed. I saw that she was going to do it, though, and closed the door, shutting the sound in. “Is this some kind of a joke?” she asked. “Some kind of perverted April fool? Untie me! Right now!”

     “Regular sacrifices keep it satisfied,” I replied. “Once a century is usually enough. One life given, and it's happy to just sit there and sleep, dreaming whatever Gods dream about. The alternative would be far worse...”

     “I said untie me now!” Tears had begun to appear at the corners of her mouth as she began to realise that this was real, that I really meant to feed her to it. “You love me!” she protested. “I know you couldn’t do this to me!”

     “William Pine loved you, but he’s dead now. If it's any comfort to you, if there’s anything on the other side of death, he’ll be there waiting for you.”

     I began the incantation. Words in a long forgotten language which I knew, from long experience, would rouse it from its slumber. The trouble was that I had been away for a long time. I should have been here, performing the incantation at least once a week to make sure it didn't slip into too deep a sleep, a sleep from which only hunger would rouse it. That had happened once, back in the sixth century AD. Egbald, the King of Wessex, had taken offence at my use of pagan magic and thrown me into a dungeon. If my son had been older I could have simply transferred my soul into him and escaped, leaving nothing but a corpse in my cell, but he was no more than a baby. I had no choice but to endure the dungeon until he came of age. In the meantime, though, Mull Vom grew hungry and emerged from his underground crypt to go hunting. He killed millions before he was finally sated. History recorded it as a plague, since he left no-one alive in the towns he visited to tell what really happened. When I was finally able to escape, I was able to lead him back, as docile as a rabbit, and return him to this very chamber, where he has remained ever since.

     I would build a garden shed over the entrance to the staircase, I thought. That way, I would be able to visit it any time I wanted, day or night. I would have to do that before I reported Sophie missing. A hole in the garden was something the police would be sure to want to investigate, no matter how much I used my magic to cloud their minds and allay their suspicion of me. And then I would have to sow some wild oats across the country, to make sure I would have descendants to transfer my soul into when my current body grew old.

     I chanted the words over and over, growing more anxious as the thing failed to respond, but eventually its eyes widened a fraction and its mouth end turned in my direction. I have no idea whether it recognised me, whether it knew that it was always the same person who came to visit it. More than likely it didn't care. What mattered was that someone was there, and that he had brought an offering.

     I stepped forward to take Sophie in my arms, but she scrabbled away across the floor away from me. “I really am sorry,” I told her. “I'm not a bad man. I'm doing this to save lives. You have no idea what Mull Vom is capable of. It can change size and form, become a thing you cannot imagine. No weapon of man can stop it. Guns, bombs, missiles, all would be completely useless. Only this can keep it contained. I know how scared you must be, but you will be saving your country from a calamity greater than the second world war.” She could only stare at me, though, silently shaking her head as she continued to retreat across the slimy stone floor.

     I stepped forward and scooped her up. She struggled and kicked madly, but I'd tied her tightly and she was helpless in my arms. I then carried her over to Mull Vom. The thing reached out eagerly with its arms. One of its fingers brushed against mine as it took her, and I shuddered at the cold, clammy feel of it. I can only imagine what it must have been like for Sophie to feel those hands on her bare skin.

     It turned her so that her head was towards it and it opened its mouth. She screamed again as the thing's loose, flabby lips fastened on the top of her head and slipped wetly down her face, sucking and slurping as they went. Her screams were cut off abruptly as they covered her mouth. Then they opened wider to make room for her shoulders as it lifted her higher. It paused for a moment, as if gathering its strength, then lifted its mouth up towards the high ceiling, allowing Sophie to slide down its gullet. A moment later only her feet and ankles could still be seen, still tied together by the strong, white rope, and then they also disappeared from view with an audible sound of suction that I found quite unpleasant.

     The creature’s body was buffeted from within as Sophie, who must have been quite insane with terror by now, continued to struggle, but a few moments later she finally died, either from suffocation or the creature's digestive acids. I left it to digest her in peace, closing and locking the door behind me and climbing back up the stairs. As I reached the top, I saw all the houses around me still with dark windows, their occupants still peacefully asleep. They had no idea of the calamity I had saved them from, and hopefully they never would. The country was safe for another hundred years.

     I returned to the house, got undressed and went back to bed. I would have to be up early tomorrow morning for my commute back to the antiques shop.